Acta Phys. -Chim. Sin. ›› 1986, Vol. 2 ›› Issue (02): 133-140.doi: 10.3866/PKU.WHXB19860206

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A STUDY ON THE SOLVATION OF Na IN BINARY MIXTURE OF SOLVENTS BY Na-23 NMR

Huang Yining; Li Zhifen; Liu Ruilin   

  1. Institute of Physical Chemistry, Peking University
  • Received:1984-12-17 Revised:1985-09-28 Published:1986-04-15

Abstract: ~(23)Na~+ chemical shift of NaClO_4 in mixed solvents of water-acetone,water- acetonitrile, and water-ethanol and of NaBPh_4 in methanol-DMF, methanol-benzene, and methanol-dioxane were measured. By means of iso-solvation point the sol- rating abilities were compared as water>acetone≥acetonitile≥ethanol and DMF> methanol. The preferential solvation free energies of Na~+ for the pairs solvenst, methanol-DMF and water-acetone, were evaluated as -2.7 kJmol~(-1) for DMF to methanol and 4.6 kJmol~(-1) for acetone to water.
~(23)Na~+ chmical shift in methanol-benzene is independent of the content of benzene. It verified the simple solvation modle for ion in methanol-inert solvent mixture. However the chemical shift of ~(23)Na~+ in methanol-dioxane mixture varies with the composition of solvent. The linewidth of Na-23 resonance peak increases dramtically with the increasing of dioxane. It seems that the dioxane molecules disturb the primary solvation shell of Na~+ in methanol and result a unsymmetrical immediate surrounding for Na~+ cation.